<?php
/**
 * Smarty plugin
 *
 * This plugin is only for Smarty2 BC
 * @package Smarty
 * @subpackage PluginsFunction
 */

/**
 * Smarty {math} function plugin
 *
 * Type: function<br>
 * Name: math<br>
 * Purpose: handle math computations in template
 *
 * @link http://www.smarty.net/manual/en/language.function.math.php {math}
 *       (Smarty online manual)
 * @author Monte Ohrt <monte at ohrt dot com>
 * @param $params array
 *       	 parameters
 * @param $template Smarty_Internal_Template
 *       	 template object
 * @return string null
 */
function smarty_function_math($params, $template) {
	static $_allowed_funcs = array ('int' => true, 'abs' => true, 'ceil' => true, 'cos' => true, 'exp' => true, 'floor' => true, 'log' => true, 'log10' => true, 'max' => true, 'min' => true, 'pi' => true, 'pow' => true, 'rand' => true, 'round' => true, 'sin' => true, 'sqrt' => true, 'srand' => true, 'tan' => true );
	// be sure equation parameter is present
	if (empty ( $params ['equation'] )) {
		trigger_error ( "math: missing equation parameter", E_USER_WARNING );
		return;
	}
	
	$equation = $params ['equation'];
	
	// make sure parenthesis are balanced
	if (substr_count ( $equation, "(" ) != substr_count ( $equation, ")" )) {
		trigger_error ( "math: unbalanced parenthesis", E_USER_WARNING );
		return;
	}
	
	// match all vars in equation, make sure all are passed
	preg_match_all ( "!(?:0x[a-fA-F0-9]+)|([a-zA-Z][a-zA-Z0-9_]*)!", $equation, $match );
	
	foreach ( $match [1] as $curr_var ) {
		if ($curr_var && ! isset ( $params [$curr_var] ) && ! isset ( $_allowed_funcs [$curr_var] )) {
			trigger_error ( "math: function call $curr_var not allowed", E_USER_WARNING );
			return;
		}
	}
	
	foreach ( $params as $key => $val ) {
		if ($key != "equation" && $key != "format" && $key != "assign") {
			// make sure value is not empty
			if (strlen ( $val ) == 0) {
				trigger_error ( "math: parameter $key is empty", E_USER_WARNING );
				return;
			}
			if (! is_numeric ( $val )) {
				trigger_error ( "math: parameter $key: is not numeric", E_USER_WARNING );
				return;
			}
			$equation = preg_replace ( "/\b$key\b/", " \$params['$key'] ", $equation );
		}
	}
	$smarty_math_result = null;
	eval ( "\$smarty_math_result = " . $equation . ";" );
	
	if (empty ( $params ['format'] )) {
		if (empty ( $params ['assign'] )) {
			return $smarty_math_result;
		} else {
			$template->assign ( $params ['assign'], $smarty_math_result );
		}
	} else {
		if (empty ( $params ['assign'] )) {
			printf ( $params ['format'], $smarty_math_result );
		} else {
			$template->assign ( $params ['assign'], sprintf ( $params ['format'], $smarty_math_result ) );
		}
	}
}

?>